1. Field of the Invention
The present invention relates generally to the field of electronic apparatus, more particularly to the field of electronic switched-output controller apparatus, and still more particularly to electronic, multiple switched-output, such as switched-power or switched-signal, controller apparatus.
2. Background Discussion
With the ever-increasing use in business and government of computers and computer work stations, and related equipment such as monitors, disc drives and printers, there is a corresponding increased need for electronic equipment to control the operation thereof. For example, power controllers are frequently used to power-up and power-down such electronic apparatus, or switched-output control apparatus may be used for providing low-voltage or signal inputs to electronic apparatus requiring such inputs for operation.
As an example of switched power needs, when a number of current-drawing electronic apparatus, such as computers, disc drives and printers, are connected to a common building electrical outlet, turning on all the apparatus at the same time can result in a combined high start-up current spike. Such a turn-on power spike may be sufficiently high to trip the circuit breaker associated with the building electrical outlet supplying power to the apparatus, even though the combined steady-state current requirements of all the apparatus are within the current capacity of the circuit. Without time-delay sequencing of the turning on of the equipment, there is needed either a higher current capacity building circuit or more than one building outlet circuit--neither of which may be available or practical to provide in already-constructed offices or buildings. An appropriately configured, switched power controller which provides time-delay turn-ons for the various pieces of electronic equipment, so that they do not all turn on at the same instant, can typically remedy this problem of high cumulative start-up current spikes without requiring special or multiple building circuits.
On the other hand, even if the available building circuit capacity is capable of handling high start-up current spikes caused by the simultaneous turning on of a number of pieces of electrical or electronic equipment, it may be required or desired to turn on certain pieces of the equipment before others are turned on. For example, it may be required to turn on a stand-alone disc drive so that it is "up and running" before the associated computer is turned on. Similar delayed turn-off of several pieces of some electronic or electrical equipment may be needed.
Other situations requiring the controlled turning on and off of electrical power or operating signals to electronic or electrical equipment are unattended installations of such equipment or location of such equipment in remote or relatively-inaccessible places. It may, for example, be desired to turn off unattended computers or computer systems whenever they are not used for a predetermined length of time and to turn them back on when they are addressed. It may also be desired to turn off certain unattended or remote electronic equipment, such as computers, fans, or pumps, when monitored ambient conditions, such as temperature, pressure and/or humidity exceed or fall below predetermined limits and to turn the equipment back on when the ambient conditions return to acceptable values.
By way of a still further example, it may be necessary, for equipment protection, to turn off certain pieces of equipment when the available line voltage exceeds or falls below safe equipment operating limits and to turn the equipment back on when the line voltage returns to a safe operating level for a preestablished period of time.
Thus, present requirements for switching controls to turn on and off electrical and electronic equipment and/or to provide switching signals to electronic apparatus are virtually limitless. However, these requirements tend to be highly individualized since many electrical or electronic equipment installations are customized to meet individual user requirements.
Multiple time delay power controllers such as are, for example, disclosed in U.S. Pat. No. 4,769,555 to Pequet, et al., are useful for switched power controlling situations. However, they and other switched output controllers tend to be uneconomical when only one or a few of the switched-output controllers of a particular configuration are required by customers. The principal reason for this is because such switched-output controllers have heretofore, so far as is known to the present inventors, required to be constructed using customized, "hard wired" circuit cards or boards to which are mounted individual electronic components or circuits.
It may, of course, be feasible in some instances for a switched-output controller manufacturer to vary some simple output timing functions in a particular type of switched-output controller to meet different user requirements simply by changing the resistance or capacitance in one or more R-C timing circuits in the controllers. However, more varied customer requirements usually require the redesign of major portions of the switched-output controller, with the consequent necessity for the laying out and fabricating of entirely different circuit boards or cards for most customers having substantially different switched-output controller input/out requirements.
This requirement for redesign and manufacture of switched-output controllers for many different functional control requirements (i.e., operational protocols) of customers usually results in undesirably high unit switched-output controller costs. This is particularly the situation if individual customer controller procurements are so small that the redesign costs cannot be amortized over a large number of controllers. Moreover, even if unit cost is not a limiting factor, such switched-output controller redesign can result in the inability to meet tight customer delivery schedules.
These problems often result in customer dissatisfaction and loss of business, particularly for small switched-output controller manufacturing companies which tend to specialize in custom applications, as opposed to large manufacturers which tend to be awarded large contracts--such as government contracts--for providing a large number of the same type of switched-output controller apparatus.
For these and other reasons, the present Applicants have invented an improved, generally universal switched-output controller apparatus that incorporates a programmable microcontroller that can be configured to provide a variety of switched power and/or signal outputs which are responsive to a variety of inputs and which satisfy a variety of customer operational protocols. The present switched-output control apparatus, which may be designated a one time programmable ("OPT") switched-output controller because once programmed it cannot be reprogrammed, enables the economical customizing of a single or only a few standard types of switched-output controller apparatus according to the different operating specifications of different customers without the need for circuit redesign and the manufacture of customized circuit cards or boards.